CNRFC - Hydrology - Observed River/Reservoir Conditions

MERCED RIVER - YOSEMITE NP AT HAPPY ISLES (HPIC1)

Latitude: 37.73º N	Longitude: 119.56º W	Elevation: 4017 Feet
Location: Mariposa County in California		River Group: San Joaquin

Monitor Stage: N/A

Flood Stage: 7.5 Feet

Observed Data Credit
	Raw streamflow data is provided by the US Geological Survey (USGS). View USGS Data for this station location.

Historical Stage/Flow Data
Note: Water Year 2025 is currently showing peak daily mean values. These will be updated to instantaneous peaks in the coming months.
Water Year	Peak Discharge (cfs)	Stage (feet)	Date
Most Recent 5 Years
2025	2,100	5.89	May 11, 2025
2024	2,980	6.80	May 19, 2024
2023	4,980	8.42	May 23, 2023
2022	2,430	6.25	Oct 25, 2021
2021	1,410	5.02	May 7, 2021
Historical High Stage/Flow Events (Period of Record - Aug 1915 to Present) - Ranked by Flow
1997	10,100	13.27	Jan 2, 1997
1956	9,840	12.73	Dec 23, 1955
1951	9,260	11.55	Nov 18, 1950
1965	9,240	11.50	Dec 23, 1964
1938	8,400	10.40	Dec 11, 1937
2018	8,060	10.09	Dec 07, 2018

Location Photographs
Upstream Photo	Gage House Photo	Downstream Photo

ESRI™ Locator Map

Official 7 Day National Weather Service Forecast (CAZ324)

Tonight: Clear. Lows 27 to 37. Northeast winds up to 10 mph.

Friday: Sunny. Highs 49 to 55. East winds up to 5 mph shifting to the west in the afternoon.

Friday Night: Mostly clear in the evening then becoming mostly cloudy. Lows 32 to 40. East winds up to 5 mph.

Saturday: Partly sunny. Highs 48 to 56. South winds up to 15 mph.

Saturday Night: Mostly cloudy. Lows 31 to 39. Southeast winds 5 to 10 mph.

Sunday: Partly sunny. Highs 44 to 52.

Sunday Night: Chance of rain and snow in the evening, then rain and snow likely after midnight. Moderate snow accumulations. Lows 29 to 37. Chance of precipitation 60 percent.

washingtons birthday and Monday Night: Snow showers and rain showers. Snow may be heavy at times. Heavy snow accumulations. Highs 37 to 43. Lows 26 to 34. Chance of precipitation near 100 percent.

Tuesday: Snow showers in the morning, then snow showers and rain showers in the afternoon. Snow may be heavy at times. Heavy snow accumulations. Near steady temperature in the lower 30s. Chance of precipitation 90 percent.

Tuesday Night: Mostly cloudy. Snow showers in the evening, then chance of snow after midnight. Snow may be heavy at times in the evening. Heavy snow accumulations. Lows 22 to 30. Chance of snow 80 percent.

Wednesday: Partly sunny with a 50 percent chance of snow. Highs 34 to 40.

Wednesday Night and Thursday: Snow likely. Heavy snow accumulations. Lows 24 to 32. Highs 34 to 40. Chance of snow 70 percent.

Flood Impacts
13.27 Feet	Flood of Record: 1/2/97. $178 million in damage to Yosemite Valley.
10.0 Feet	Northside Drive at Wosky Pond, Southside Drive at Chapel Meadow, El Capitan crossover, and Sentinel crossover are impassable to vehicles.
8.2 Feet	Swinging Bridge overtops. Water on road at Northside Drive, Southsie Drive, El Capitan crossover, and Sentinel crossover.
7.5 Feet	Flood Stage. Housekeeping camp and Yosemite Valley backpacker campground begin to flood.
7.0 Feet	North Pines and Lower Pines campgrounds begin flooding.

Product Disclaimer

This river graphic is not intended to serve as a substitute for official flood watches, warnings, advisories, or statements issued by the NWS San Joaquin Valley-Hanford Weather Forecast Office. Observations are preliminary and subject to change. River levels identified as "forecast" should be consistent with those contained in official NWS products. River levels identified as "guidance" have significant uncertainty due to future weather or reservoir regulation and are provided for planning purposes only.

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